Apparatus for shearing a stream of material



A ril 22, 1958 c. R. P. CASH 2,331,753

APPARATUS FOR SHEARING A STREAM OF MATERIAL Filed April 22, 1954 2 Sheets-Sheet 1 F1 [EL].

4 IN VEN TOR. CHARLES RP. CASH C. R. P. CASH April 22, 1958 2,831,753

APPARATUS FOR SHEARING AsTREAM OF MATERIAL Filed April 22, 1954 2 Sheets-Sheet 2 FIE-E 'FIE EI 7 INVENTOR.

CHARLES RP CASH United States Patent APPARATUS FOR SHEARIN G A STREAM 0F MATERIAL Charles R. P. Cash, Antioch, Calif., assignor to Fibreboard Paper Products Corporation, a corporation of Delaware Application April 22, 1954, Serial No. 424,978

Claims. (Cl. 23-267) manufacture of paper.

Among the objects of the invention is the provision of an apparatus for continuously mixing a stream of very hot molten liquid with a mass of cooler liquid.

Another object of the invention is to provide apparatu for dissolving a very hot molten chemical in an aqueous solvent.

A more direct object of the invention is to prevent the occurrence of dangerous and costly steam explosions in the dissolving liquor tank when smelt is added to the liquor. These explosions are caused by local overheating and rapid steam formation in the liquor by hot accumulated masses of smelt.

In accordance with the present invention, a hot liquid, such as smelt, which is a molten glassy material at about 1600 F., is fed through conduit means in a continuously falling stream into a body of cool dissolving liquid or solvent. The flowing stream is continuously sheared or broken at timed intervals, preferably equal intervals, to positively divide the stream into small units. The shearing forces are applied laterally to the flowing stream.

This may be accomplished with the aid of a plurality of spaced apart shearing blades or paddles mounted for lateral movement below the conduit means. These blades are preferably mounted for horizontal rotation, especially when the cool liquid container is a vertical cylindrical tank, and may be operatively connected for movement -to any convenient power means.

The small divisions or units separated from the hot liquid stream are continuously transported and distributed over the surface of the cool liquid by laterally moving or rotating the shearing blades, and are continuously caused to fall into the cool liquid. The cool liquid may be continuously agitated to guard additionally against any accumulation of masses of hot liquid and local overheating, and to facilitate the dissolving of the hot liquid in the cool liquid. Such breaking up of the molten hot stream into small units, is especially important in preventing sudden vaporization or steam formation which would otherwise occur if large masses of the hot liquid were introduced into the dissolving liquidat one time; and dangerous bumping or explosive pressure changes in the cool liquid are obviated.

cooking liquor or;black liquor.

second smelt spout is not shown in the view because it is part of the broken-away portion. U

' Fig. 3 is a sectional view taken in planes indicated by line 3-3 of Fig. 2. It shows the shearing blades on the mounting ring, which in turn is shown mounted onthe solution agitator drive shaft. Spray cooling means for the shearing assembly, and the end of the smelt spout are also shown; I

Fig. 4 is a sectional view taken on line 4-4 of 2 showing a detail of the ring carrying the shearing blades and an inner retaining wall. An outer retaining wall is shown attached to the shearing blades.

Fig. 5 is a view in perspective of a portion of the shearing assembly with part of the outer retaining wall broken away to show the outer ends of several shearing blades. A portion-of a support arm also is shown I In the sulfate or kraft pulp process, wood chips'are cooked under steam pressure in a cooking liquor containing essentially sodium sulfide and caustic soda. The pulp produced in the operation ,is separated from the spent Recovery of the chemicals from the black liquor is an important factor in the economic balance of the process. I

The black liquor is first concentrated in any suitable manner to produce a liquor sufliciently high in organic matter to ignite and burn when sprayed into a smelt furnace 2 (Fig. 1). By combustion in the furnace, the organic matter in the liquor is consumed with the evolution of sufficient heat to melt the inorganic residue and produce a pool of smelt. The smelt, consisting essentially of sodium carbonate and sodium sulfide, collects in.

the bottom of furnace 2 and overows into smelt spout 3.

The flow of smelt in spout 3, although continuous, is frequently irregular and abnormally large. This may be due to such unavoidable factors as partial blocking of the spout by scale or crust followed by sudden unblocking, or to sudden pressure changes in the furnace caused by the turbulence of the combustion reactions taking place therein. Whatever the cause, the sudden rushes of abnormally large masses of smelt, at about 1600 F., through spout 3 into the aqueous dissolving liquor, which is usually a weak soda solution, cause dangerous and costly explosions in the dissolving liquor tank. Such explosions are avoided by applying the method and apparatus of this'invention to the problem in the following manner.

Smeltissuing from the delivery end of spout 3 ina continuous but sometimes irregular stream is caused to fall continuously toward the outer periphery or edge 4 of a frusto-conical ring 6 having a smooth smelt receiving surface 6., Ring 6 is fastened to support arms 7 by motor 23, as shown in'Fig. 1.

=as'indicated in Fig. 1. I Welded-to the inner-edge of ring 6 (Fig. 4), is an inner retaining wall 12; and a plurality of equally spaced apart shearing blades or paddles 13 are Welded to ring surface 6. The shearing blades are vertically disposed and project beyond and below the outer edge 4- of ring 6; and it will be noted that since spout 3 is so located as to cause the stream to fall toward the periphery of ring 6, the moving blades are alined in substantially the same upright direction in which the stream flows when theypass by the stream and shear .the same. Welded to the outer. endsof blades 13 concentric with ring'6 is an outer retaining wall 14.

:The descending stream of smelt fallson the smelt receiving surface 6' of rotating ring 6, as a downwardly stretching sheet or curtain of the character of molten glass. The ring 6 is rotated at such a. rate relative to the spacing of blades 13 and the averagerateof flow of the smelt streamthrough spout 3,.so..as. to cause the lowest level reached by the-main stream of smelt between two blades and before it ispo'sitively sheared .orbroken by the blade next in line, to coincideapproximately with the lowest point of the bladev breaking the stream.

.After the stream is positivelybroken by a blade, the broken unit flows downwardbetween a pair of blades; and the main stream becomes again broken by anadjacent oncoming blade with the result thatonly relatively small masses or units of the smelt can fall freely. intothe dissolving liquor which is indicated M16 in tank 17.

Such cycle of operation is repeated continuously as ring 6 is continuously rotated.

The effect of this action is tocause eachof the masses or units which are beingsheared from the main stream to be simultaneously carried laterallybythe blade 13 that has divided the same, out of the way of the oncoming main stream. This is so because the shearing is not a mere cutting of the stream by a relativelysharp edge but by a shearing surface of substantial width. As a .result, the divided units of smelt are individually distributed over the surface of the dissolving liquor. Thus, accumulation of relatively large masses of..the smelt is prevented from suddenly striking the liquor at one point, and causing suflicient local .internal overheating of the liquor as such large mass falls therethrough, which would result in a large vapor bubble and a consequent violent explosion.

The dissolving liquor is agitated. in a conventional manner whilethe smelt is introduced therein to expedite solution and dissipation of heat. This may be conveniently accomplished by attaching any. desired number of agitating paddles 18 to shaft 9 which is journalled in bearings 19. If desired, however, a separately driven agitator may be employed.

The solution, which is so-ealled green liquor, continuous'ly formed in tank 17 is pumped from the bottom of the tank through line 21 by means of a pump 22driven Aportion of the green liquor is fed continuously to spray nozzles 24 and 26 through lines 27, '23 and'29; and another portion is bypassed to U-shap'ed pipe'31 throughfeed line' 32. Pipe '31 is provided with a multiplicity of spaced holes (not shown) along its entire bottom surface. The sprays of relatively cool green liquor from nozzles 24 and 26 and pipe 31 serve to prevent the ring assembly and the spout, respectively, from becoming overheated, and assist in dissolving or washing smelt from the ring assembly.

Make up water is added to the tank in the usual manner; and the green or soda dissolving liquor continuously overflows tank 17 through overflow 33 opening into standpipe 34. The green liquor is continuously withdrawn from a standpipe 34 and transferred to a recausticizing unit (not shown) through line 36. unit the green liquor is treated in the usual manner for recovery of the chemicals therein.

Although the invention has been found particularly applicable in dissolving smelt in dissolving liquor, many in the recausticizing modifications thereof are-possible,-as it is to be'understood it can be employed in any environment where the problem exists of preventing explosions or other undesirable factors which would otherwise result from introduction of a relatively hot molten glass-like stream of material into a relatively cool liquid.

I claim:

1. Apparatus for dividing a molten stream into relatively small units comprising a ring adapted to rotate about an upright axis in a substantially horizontal plane, said ring having a frusto-conical surface upon which the stream is adapted to fall adjacent the periphery of said frusto-conical surface when the ring is positioned with the base of saidsurfac'e lowermost, a plurality. of upright spaced apart imperforatc shearing blades of substantial width mounted on said surface and projecting beyond the outer edge thereof, the outer ends of said blades projecting below the ring, and an upright cylindrical wall secured to such outer ends and spanning the spaces between said blades.

2. Apparatus for dividing a molten stream into relatively small units comprising a ring adapted to rotate about an upright axis in a substantially horizontal plane, said ring having a frusto-conical surfaceupon which the stream is adapted to fall adjacent the-periphery of said frusto-conical surface when the ring is positioned with the base of said surface lowermost, a plurality of upright spaced apart imperforate shearing blades of substantial width mounted on said surface and projecting beyond the outer edge thereof, the outer ends of'said blades projecting below the ring, an upright cylindrical wall secured to and spanning such outer ends, and an upright cylindrical retaining wall secured to the inner edge of the ring.

3. The combination with a tank adapted to contain a dissolving liquid into which a molten'stream is adapted to flow from a spout located above the tank, of apparatus for positively dividing said stream into relatively small portions before it hits said liquid comprising a ring, means mounting said ring for rotation about an upright axis and in a'substantially horizontal plane above the liquid level in said tank, said ring having a surface sloping downwardly and outwardly toward the'periphery thereof to provide a stream'receiving surface movable substantially under said spout so that the stream can fall onto said surface, and a plurality of upright spaced apart shearing paddles of substantial width mounted on said small portions'before it hits said liquid comprising a ring,

means mounting said ring for rotation about an upright axis and in a substantially horizontal plane above the liquid level in said tank, said ring having a surface sloping downwardly and outwardly toward the periphery thereof to provide a stream receiving surface movable substantially under said spout so that the stream can fall onto said surface, a pluralityof upright spaced apart shearing paddles of substantial width mounted on said surface to divide said stream into said relatively small portions and move such portions laterally out of the way of said stream, whereby said portions can flow into the tank from spaces between the paddles, and means for applying a washing and cooling liquid to said surface.

5. The combination with a tank adapted to contain a dissolving'liquid into which a molten stream is adapted to flow from asp'outlocated above theta'nk, of appa- 'ratus 'for 'positively dividing said stream into relatively small portions before it hits said liquid comprising a ring, means mounting said'ring for rotation about an upright axis and in a substantially horizontal plane above the liquid level in said tank, said ring having a surface sloping downwardly and outwardly toward the periphery thereof to provide a stream receiving surface movable substantially under said spout so that the stream can fall onto said surface, a plurality of upright spaced apart shearing paddles of substantial width mounted on said surface to divide said stream into said relatively small portions and move such portions laterally out of the way of said stream, whereby said portions can flow into the tank from spaces between the paddles, and means for removing liquid from said tank and conducting it onto said surface to cool the same and wash material therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 1,399,848 Carlson Dec. 13, 1921 1,483,241 Opderbeck Feb. 12, 1924 1,671,683 Podszus May 29, 1928 1,753,019 Page Apr. 1, 1930 2,007,799 Gloersen July 9, 1935 2308.769 Meinzer Jan. 19, 1943 

5. THE COMBINATION WITH A TANK ADAPTED TO CONTAIN A DISSOLVING LIQUID INTO WHICH A MOLTEN STREAM IS ADAPTED TO FLOW FROM A SPOUT LOCATED ABOVE THE TANK, OF APPARATUS FOR POSITIVELY DIVIDING SAID STREAM INTO RELATIVELY SMALL PORTIONS BEFORE IT HITS SAID LIQUID COMPRISING A RING, MEANS MOUNTING SAID RING FOR ROTATION ABOUT AN UPRIGHT AXIS AND INA SUBSTANTIALLY HORIZONTAL PLANE ABOVE THE LIQUID LEVEL IN SAID TANK, SAID RING HAVING A SURFACE SLOPING DOWNWARDLY AND OUTWARDLY TOWARD THE PERIPHERY THEREOF TO PROVIDE A STREAM RECEIVING SURFACE MOVABLE SUBSTANTIALLY UNDER SAID SPOUT SO THAT THE STREAM CAN FALL ONTO SAID SURFACE, A PLURALITY OF UPRIGHT SPACED APART SHEARING PADDLES OF SUBSTANTIAL WIDTH MOUNTED ON SAID SURFACE TO DIVIDE SAID STREAM INTO SAID RELATIVELY SMALL 